I like most people have been having more problems with stable temps since adding my Metal Halide lights. Before the MH lights my temperature was a constant 82 degrees, with no variation at all. The fans ran most of the time, cooling faster than the water heated up, and the heaters would flicker on and off keeping it at exactly 82. Of course, there was more electricity being used, but my concern was not my electric bill. As a matter of fact, I did not notice it go up if it did.
Now with the Metal Halides, and fine tuning heaters, and fans, my temperature right now fluctuates from 81.7 to 83.9. By late afternoon, after the Metal Halides have been on, the temp peaks at 83.9, the MH goes off then, and within two hours the tank is back down to 82.4 and then slowly by morning when the lights are just getting ready to come on.. The temp is the lowest at 81.7.
I have not noticed any stress on any of my livestock. Every fish and every coral are healthy, eating well, swimming well, and seem to be enjoying their little home I have tried to creat for them. I am not going to stress at this time. When I can either afford it, or come up with some DIY I can afford and make I will add in a CHILLER of some type to try and achieve perfection. I think a two degree swing in the 82 degree range as the one I have is not a big problem at all.
I do have a low temp alarm set to 81.5 degrees, and a high temp alarm set to 84 degrees. If I ever start hearing those go off with any sort of regularity, I will hurry my plans for a cooling device. I am learning patience. ROME was not built in a day, and neither will Dave's Ocean be LMAO
But I do love this hobby... it is the most fascinating hobby I have ever had in my life. Watching that tank grow and change is very enjoyable, and very beautiful to see.
Dave